We will extend our investigations of glucose and amino acid metabolism in skeletal muscle using the isolated perfused rat hindquarter and the soleus muscle preparations. Our aims are as follows: (1) To study the basis for insulin resistance in muscle in diabetic ketoacidosis. We will assess whether insulin resistance can be overcome by inhibiting fatty metabolism and if restoration of insulin sensitivity requires synthesis of new protein. We will also determine whether "diabetogenic pituitary peptide" depresses insulin-stimulated glucose uptake solely due to inhibition of glycogen synthase or whether it has an independent effect on glucose transport. (2) To determine why a "permissive" amount of insulin is required for exercise to stimulate glucose uptake. We will explore the relationship between the release of "muscle activity factor" by the soleus and its ability to respond to electrical stimulation with an increase in glucose uptake. In addition, we will determine whether electrical stimulation alters the binding of insulin to muscle. (3) To evaluate whether freeze-etching can be used to demonstrate morphological alterations in the sarcolemmal membrane when glucose uptake is stimulated or when muscle is insulin resistant. (4) To study the effect of diabetes, ambient amino acid concentration and various nutritional and hormonal pertubations on the pattern of amino acid release from muscle. As part of these investigations we would develop methods for evaluating the magnitude of protein synthesis and proteolysis in the hindquarter. (5) To determine the basis for the inhibition of amino acid release from skeletal muscle by adrenergic agents. We will also evaluate the effect of isuprel on protein catabolism in man. (6) To assess the mechanisms by which alanine and glutamine are formed in muscle. We will determine which amino acids are good nitrogen sources and whether a significant proportion of the pyruvate used for alanine formation can be derived from citric acid cycle intermediates.